From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f200.google.com (mail-pf0-f200.google.com [209.85.192.200]) by kanga.kvack.org (Postfix) with ESMTP id 7200C6B0003 for ; Tue, 27 Feb 2018 19:03:27 -0500 (EST) Received: by mail-pf0-f200.google.com with SMTP id h11so345949pfn.0 for ; Tue, 27 Feb 2018 16:03:27 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id p19sor124447pfh.49.2018.02.27.16.03.25 for (Google Transport Security); Tue, 27 Feb 2018 16:03:25 -0800 (PST) Date: Wed, 28 Feb 2018 09:03:19 +0900 From: Minchan Kim Subject: Re: [PATCH] mm/zsmalloc: strength reduce zspage_size calculation Message-ID: <20180228000319.GD168047@rodete-desktop-imager.corp.google.com> References: <20180226122126.coxtwkv5bqifariz@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180226122126.coxtwkv5bqifariz@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: Joey Pabalinas Cc: linux-mm@kvack.org, Nitin Gupta , linux-kernel@vger.kernel.org Hi Joey, On Mon, Feb 26, 2018 at 02:21:26AM -1000, Joey Pabalinas wrote: > Replace the repeated multiplication in the main loop > body calculation of zspage_size with an equivalent > (and cheaper) addition operation. > > Signed-off-by: Joey Pabalinas > > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c > index c3013505c30527dc42..647a1a2728634b5194 100644 > --- a/mm/zsmalloc.c > +++ b/mm/zsmalloc.c > @@ -821,15 +821,15 @@ static enum fullness_group fix_fullness_group(struct size_class *class, > */ > static int get_pages_per_zspage(int class_size) > { > + int zspage_size = 0; > int i, max_usedpc = 0; > /* zspage order which gives maximum used size per KB */ > int max_usedpc_order = 1; > > for (i = 1; i <= ZS_MAX_PAGES_PER_ZSPAGE; i++) { > - int zspage_size; > int waste, usedpc; > > - zspage_size = i * PAGE_SIZE; > + zspage_size += PAGE_SIZE; > waste = zspage_size % class_size; > usedpc = (zspage_size - waste) * 100 / zspage_size; > Thanks for the patch! However, it's used only zs_create_pool which is really cold path so I don't feel it would improve for real practice. Thanks. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org